ISAF vs KITE Sailing

[Doug Lord]

Apparently, the ISAF has decided to withhold recognition of any record established by a boat using a kite for power.
To me this is simply unacceptable and a gross overreach by ISAF. Kites have been a part of speed sailing events for years.
It seems to me that if they can take this kind of action with kites why couldn't they just arbtrarily ban hydrofoils like the ones in the Moth Class or Neil Pryde's foiling windsurfer or canting keels or?
If anyone has any insight as to why this is being done and the precedent it sets I would be most interested to hear it...

[Tim B]

is there a clause that states something along the lines of "The power-producing element must be rigidly attatched to the boat"?
I don't know, but if there is, then it would seem that a kite is not "rigidly attatched" and therefore does not count.

also, think about the design challenge. the request is completely different from a normal rig.

Tim B.

[Doug Lord]

Tim, spinnakers are not rigidly attached. But there is a more important point: kites have been involved in speed sailing for years so why change the rule now?
Why should the ISAF issue a "top down" ruling that impacts what kind of boat sailors can sail? Or what kind of sail they can use? Remember, this ruling effectively bans kites from being used in speed sailing-an area that has traditionally been anything goes. To me it seems that they go way too far and set a precedent that could be applied to other technologies like hydrofoils.
To arbitrarily remove a promising speed saling technology from speed record contention(after years and years) will just diminsh the value of future speed records since kites WILL be sailed and they WILL get fast enough to be in contention for records that the ISAF says they will not be recognized for . When that happens the ISAF recognized record will be meaningless.
Nobody interested in the development of sailing technology should fail to recognize the potential implications of this kind of overbearing bureacracy...

[Kiteship]

is there a clause that states something along the lines of "The power-producing element must be rigidly attatched to the boat"?
I don't know, but if there is, then it would seem that a kite is not "rigidly attatched" and therefore does not count.

also, think about the design challenge. the request is completely different from a normal rig.

Tim B.

In response to your question, Tim; yes, kite-powered craft are currently allowed in speed sailing, have been allowed--and encouraged--since at least 1977. Dozens of kiteboats have participated over the years; one held the C-class world record for a number of years. Second, kite sail powered boats are numerous; there are approximately 150,000 kitesurfers in the world today and dozens of kite-powered "proper" boats. Have a look at our website for what's going on in mainstream sailing and kites: http://www.kiteship.com

Please also note that the ISAF ban does not just effect flat water, extreme speed attempts, but encompasses ALL of the offshore and inshore point-to-point timed record events that the WSSRC coordinates (165 different point-to-point, 24-hr timed, round-world, etc, etc, at last count)

Yours,

Dave Culp

[usa2]

not to sound somewhat negative about kites or anything, but arent most speed sailing records set with the apparent wind forward of the beam while kites are most efficient welll off the wind? If that is true, then a boat would only be able to set a record if it could sail as fast as the wind, and the wind was blowing at least 45 knots. Also, in regards to the rule thing, does anyone know if there is a clause about sails having to be set from the mast? The way i interpreted it(forgive me if i am incorrect), one of the kite's advantages is that it isnt attached to the mast, which eliminates the danger of a knockdown. Maybe they dont think it is technically a sail, if its just flying out in front of the boat. Spinnakers are what you could call "rigidly" attached- at the top of the mast, and at the end of the pole. kites are less attached than a conventional spinnaker, and with todays boats all starting to use A-sails, most free flying sails are becoming slow. with an A-sail, your still able to sail faster than the wind. Is it possible to exceed the wind speed with a kite?

[daveculp]

Usa2;

Your last question should have been your first. ;-)

Yes, kite boats are quite capable of sailing faster than the wind--much fasterr. Kiteboats can sail on any courses that "real" sailboats can sail. Kite buggies (on land) sail at 3-5 times windspeed, just like landsailers. In the only engineering drawing in his 1827 book "Aeropleustic Art" Briton George Popcock clearly described how to sail upwind. (Yes, that was 1827; 178 years ago). As I said in my earlier post, kites are sails, have been so defined by the rulesmakers for many, many years. Turn your logic around and look at it; what makes mast-attached sails more "real" than free-flying sails? Because they came first? Didn't the stone age come before the iron age? Did that make it better?

This isn't theoretical stuff; kitesailing is a mature, long-lived existing industry. Which is why this move by ISAF is so puzzling, and seemingly unfair. In actual fact, kite sailed boats are faster, stabler and safer than any masted sail boat (go to my web site for the reasons why, if you like)

Dave Culp
www.kiteship.com

[Andy P]

And if you look at illustrations of early (19th c ) ice sailors, they strapped 'real' kites to their backs, and gone skating/sailing.

[cyclops]

I think the ISAF is putting it's foot down because they accurately see the end of conventional sail boats racing and holding records. It sounds as if a kite boat would blow the sails off a ROUND THE WORLD RACE conventional sail boat. You can not expect them to foot the bills of races and not win.

[cyclops]

The same conditions are in effect for turbine powered boats, cars or airplanes. You can not find race classes for them.

[SuperPiper]

I wonder what the ISAF was thinking. . .

If the land speed record was set by a jet propelled car, could a person wonder if it was really an air speed record set very close to the ground? Does a kite boat start to function more like a plane than a boat? If so, then all the records have already been broken by airborne craft . . .

Rather than guessing, does anyone know the rationale used in setting the rule?

[FAST FRED]

Speed Shmeed ,
the Kite could be a far better "get home' than all the current engineering nightmares on small cruising boats ,
wing engines & foulding props, gensets with Hyd pumps , chain drive , belt drive.

FAsT FRED

[Andy P]

skate sailors :

http://home.swipnet.se/ansar/s.html

from old kites to modern wings!

[CT 249]

Dave re "In actual fact, kite sailed boats are faster, stabler and safer than any masted sail boat (go to my web site for the reasons why, if you like)"

Cogito? 18s? speed boards? G Class?????????????

[SailDesign]

Well, I guess it's no use entering races with a square-rigged boat anymore, then, since they are just multiple kites on VERY short strings tied to masts.

Sad....

[D'ARTOIS]

With a kite you don't need the canting keel - you don't need a keel either
- new era of boatdesign?

[usa2]

how do you go upwind without a keel...even if your just flying a kite?

[daveculp]

Dave re "In actual fact, kite sailed boats are faster, stabler and safer than any masted sail boat (go to my web site for the reasons why, if you like)"

Cogito? 18s? speed boards? G Class?????????????

You're a hard guy to please, Chris! Maybe if I'd just said "faster than YOUR boat"? ;-)

But, yes, existing OutLeaders can increase the average speed of the G-cats; they are a major target for us, in fact. Speed boards--Absolutely. Every year kite boards get 5-10% faster, windsurfers gain hundredths of a knot. Kites can survive, in larger sizes, in bigger winds than windsurf boards can. The performance curves will intersect soon. I'll even make a prediction on this one--within 3 years, 4 at the outside.

Cogito? That's a very hard nut to crack, as you know. Still, the answer remains yes--not with any existing kites, but if I had the budget and engineers--and the impetus, which I do not--the underlying physics still favor kites even over wingsails (they'll be "hard shell" kites; wingsails themselves. The hull will be a single ama--likely with an inflatable pod for stability at rest. All-up weight less than half of Cogito's--no rig weight and only one hull; and wetted surface--virtually all the time--will be less than Cogito's minimum, again due to the single hull and lighter weight. Yeah, Cogito can/will fall to kites, too). You can argue tactics if you like, but if the boatspeed is 10-20% faster, tactics don't matter in the long run.

Kites' advantages aren't marketing hype. They are real, and right in front of you. The salient questions are 1) how quickly will practical application equal theory, and 2) How tough is the political acceptance going to be. 1) will happen more or less quickly depending on 2) but 1) WILL happen, regardless.

Cheers,

Dave

[D'ARTOIS]

I was on your website and saw several boats equipped with your sails - I see it as a sail rather then a kite although it is a extra-proportional kite.
What I could not find is how you control this kite, till which volume you can fly one and how you launch it. Finally, where are they most efficient, under which weatherconditions, I mean?

[yipster]

http://www.twistandturn.co.uk/images/2005-Punch-Out-1-2-3.jpg http://www.twistandturn.co.uk/orBars.htm
when they came into fashion i did some very high jumps on land hanging on a bar that only had 2 strings attached to a kite that blew itself up to a foil having holes in front, you can direct them and in stacked formation you'll be really flying! never sailed them :mad:

[D'ARTOIS]

Scary......No, I saw on this Kite-site a 60 or 65 footer (AAPT) with an enormous
kite making some substantial speed. That tri that lost his mast and came back by way of this kite-configuration did not bad at all and made sometimes speed it had done under sail also - so it is a very serious thing to consider, on plain open water with no ships in the neighbourhood, otherwise it will be Chinese kiting......

[dionysis]

It's usually the case that rules forbidding something are introduced to protect the status quo. It may be as simple as that.

AFAIK, kite driven sailing boats need to be actively controlled. So if you are cruising along and want to take a nap, do you have to bring the kite down? Launching a large enough kite to drive a cruiser lookes difficult too.

[daveculp]

Hi,

The big kite aboard AAPT (420 sq meters) is ours. We spent 2 years in secrecy developing this kite, for the America's Cup race in 2003. It was legal, but not used, in that race (the syndicate which hired us was eliminated). The kite is patent pending.

Yes, it is fully controlled, very much like a spinnaker sail. It is quite easy to launch, fly and recover--it is the first kite ever to be so. At 420 sq meters we are not only 10 times as large as any other self-launched kite, it is actually a world record for largest kite ever to fly from a floating structure (the outright largest kite ever built is about 900 sq meters--we are doing the engineering now for a 1000 meter OutLeader for one of our customers)

Our company, KiteShip, is manufacturing and marketing these kites for the replacement of spinnakers; they are proven faster (stronger wind up higher) and safer (no heeling, no pressing the bows down, no broaching) than any spinnaker.

Our customers (some 4-5 dozen worldwide at this time) are mainly racers, but include cruisers, single-handers and power boats.

See our web site for more information; http://www.kiteship.com (including videos of the launch and douse); and also our discussion group for additional drawings, photos of launches, deckplans and discussion with present owners and users: http://groups.yahoo.com/group/outleader

Cheers,

Dave Culp
KiteShip

[daveculp]

how do you go upwind without a keel...even if your just flying a kite?

OutLeader kites are spinnaker replacement kites; being a specialized sail they will sail on a reach or below, not upwind. There are many upwind kites, including those made by us, none have successfully been built at large sizes and attached to large boats (though kites have been pulling boats upwind since at least 1827--yep, 178 years). There will be large upwind kites on boats within the next 3-5 years; many are working on this. They will not, however, be inexpensive. OutLeaders cost about the same as premium spinnakers--large upwind kites, which can replace the whole rig, will cost far more.

A daggerboard is required, a weighted keel is not--though most boats already have them--in order to sail any course other then dead downwind. Though OutLeaders are spinnakers, we do use the boat's keel (or centerboard) to develop sideforce--just as do any other sails or spinnakers.

Dave

[Paul B]

Hi,
Our company, KiteShip, is manufacturing and marketing these kites for the replacement of spinnakers; they are proven faster (stronger wind up higher) and safer (no heeling, no pressing the bows down, no broaching) than any spinnaker.

Our customers (some 4-5 dozen worldwide at this time) are mainly racers, but include cruisers, single-handers and power boats.

Cheers,

Dave Culp
KiteShip


Hello Dave,

Do your 48 to 60 customers worldwide include only yachts, or does that also include boards, iceboats, etc? You say most are racers. What type of races do they usually participate in?

Can you provide any results where a kite was used in a major dinghy or yacht race and prevailed? Let's not include boardsailing, only dinghies and yachts. Did your ACC client ever use your product in any of the LVC RRs? Was there ever a two boat test race within the team, a complete race not only straight-line testing, where the kite equipped boat beat the other boat around an ACC course?

Quoted from the February 2005 Seahorse Magazine report by Rob Mundle (page 20) regarding the AAPT Hobart config, quoting Langman, "We tested it (the kite sail) with no mainsail set and compared it with a conventional A-sail, and the A-sail was faster."

Why would they be testing without a mainsail? Even the photos in Seahorse show the boat sailing without a main. Is this a requirement of your kite?

Why would he say this if it is proven that the kite is faster?

The large congrats on your site seems strange considering they didn't use your product in the race. If someone only looked at the headline and didn't read the article they might be led to believe the congrats were due to your product. Why no congrats article for the Nicorette first to finish? They used a kite just as much in the race as AAPT did.

[usa2]

would you mind explaining how these upwind kites work? To me, the concept seems a bit weird, since the kite is being blown one way and you want your boat to go the other way. thanks-
usa2

[Skippy]

As for being blown the wrong way, the sail does that too. They're both at an angle wrt the boat's heading, so both of them have an athwartship component to their driving force. The keel resists that part, which leaves the forward component to drive the boat through the water. The main difference is that with the kite, you don't need the heavy keel or big wide multihull to resist the heeling moment that you get from a sail.

So ultimately, the kite is no different from a sail. It gets lift from the wind by controlling its angle of attack just like a sail does, so it's being blown in essentially the same direction as the sail. The windspeed is higher at the kite's elevation and it takes up more space. But the main difference is that the kite is tied to a free line, which has several effects:
1) The kite pulls directly along the line holding it, so as long as it's in the air, its force will be partially upward.
2) You can attach the line to the hull at a point where it won't exert any heeling moment, or where it will help counteract the overall moment exerted by the other forces acting on the boat (gravity, bouyancy, lateral resistance, and drag).
3) The direction of the kite's force doesn't change when the boat heels.
4) When the boat heels, the kite may exert a small rotational moment that helps stabilize the boat.
With no heeling moment, the driving force can theoretically be enormously greater, plus the upward component reduces the boat's displacement.


[Edited to make more sense]

[daveculp]

Hello Dave,

Do your 48 to 60 customers worldwide include only yachts, or does that also include boards, iceboats, etc? You say most are racers. What type of races do they usually participate in?

Cool! A doubter. We love you guys; keeps us honest! I'll try to answer each of your questions;

We limit the minimum size of our OutLeader kites to 35 sq meters, for several reasons. We currently fly from a yacht's existing winches, and boats smaller than aobut 22' don't have these. Also, a smaller kite requires smaller, lighter lines. W use 1/8" lines for between 35 and 70 meters which we believe are practically the smallest one can handle with gloves on. Smaller kites would need smaller lines which are dangerous to your hands. Kitesurfers get around this by never touching their lines--they always launch assisted, with the lines at full length.

Most of our currently installed kites are aboard boats that race--Corsair Trimarans, several large multis (Afterburner on the West Coast, Alacrity on the East; both 50'ers, a cat and a tri); many of our kites are aboard one-off multis, in the US, Britain and Australia. Boats from 33-48'. We are constantly pushing for races for our customers to participate in. As with most new technology, organizers are wary of us; we've been banned from some races, embraced by others, and hotly talked about by almost all.

Can you provide any results where a kite was used in a major dinghy or yacht race and prevailed? Let's not include boardsailing, only dinghies and yachts. Did your ACC client ever use your product in any of the LVC RRs? Was there ever a two boat test race within the team, a complete race not only straight-line testing, where the kite equipped boat beat the other boat around an ACC course?

Nope. We were scratched late from the Sydney Hobart (which went to windward this year), there was too little wind in the (NZ) Coastal Classic; we are right now in the 'Round North Island race, which is also going (gone?) light, it seems. We were barred from last year's Chicago Mac and also Bayview Mac, though we had boats entered in both (both went light, so the ban was moot) We are currently working on the TransPac (both the transpac and Chi-Mac are Americap races). Newly allowed multihulls in the Pacific Cup may carry kites (we're working on monos for this race, too). Americap requires polars and wind tunnel data--they say--on order to build a VPP for rating OutLeaders. We are not able to fund this work ourselves. Any ORCA race is encouraged to carry kites, but we just got this ruling, so none have, to date.NorCal PHRF is allowing kites on any boat they rate. We were closed out at last year's Double-handed Farallones race (normally a windward/leeward raced, it was a reach/reach last year), but we have 3 and possibly 4 kite boats entered this April. Please keep in mind that we were under a contractual secrecy agreement until April of 2003; we sold a grand total of 4 kites in 2003; all the remainder in 2004. It's still early days.

Quoted from the February 2005 Seahorse Magazine report by Rob Mundle (page 20) regarding the AAPT Hobart config, quoting Langman, "We tested it (the kite sail) with no mainsail set and compared it with a conventional A-sail, and the A-sail was faster."

Accurate statement. On our front page, paragraph 2 of our lead article, we admitted we blew the engineering on this kite, could not power it up on first flight. Also where we worked with AAPT's sailmaker. We re-engineered the kite and PAID THEIR SAILMAKER to make the necessary alterations. We still offer our comprehensive money-back performance guarantee--the only one in the business. FWIW, AAPT still owns their kite...

Why would they be testing without a mainsail? Even the photos in Seahorse show the boat sailing without a main. Is this a requirement of your kite?

Nope. It has been very widely documented that we train new users of our kites without any other sails flying. The crew needs to learn what the kite will, and will not do without interference from other sails, then learn to fly--and launch--behind the main. All of the publicity shots of AAPT were taken during the first--the very first--flight of the giant kite on that boat. FWIW, watch this space; this kite is going to be given a Guinness world record for largest kite ever to pull a boat.

Why would he say this if it is proven that the kite is faster?

I think I covered this above. Have you checked out our discussion list, at http://groups.yahoo.com/group/outleader? Have a look at the customer testimonials there, where folks tell us they've never sailed so fast, never felt so "on rails" sailing offwind, etc? Did you read about the older half-tonner in Perth we had 3-sail reaching with our kite--at 11 kts of boat speed (fair for a non-planing 40'er, eh?) Have a look at the photos of the J24 pulling a "tugboat" wake in Sydney haarbor last December, doing 9+ kts: http://www.pacificsailingschool.com.au/PhotoAlbums/KiteShip/ Did you also read the bit about AAPT being able to pump out all water ballast when flying the kite? This makes the 11-ton boat 3 tons lighter. D'you suppose that may have some effect on her ability to plane out at speed?

The large congrats on your site seems strange considering they didn't use your product in the race. If someone only looked at the headline and didn't read the article they might be led to believe the congrats were due to your product. Why no congrats article for the Nicorette first to finish? They used a kite just as much in the race as AAPT did.

AAPT are our customers, they spent a large amount of money to purchase our kite and to fly our people into Sydney for training; Nicorette are our competitors; how would you have put it, in our place?

I'm pulling your leg a little bit here, Paul. Your profile says you're in California. Why don't you get in touch with me, and I'll arrange for you to take a test sail? You can then come back here and tell of your own first-hand impressions, good or bad. I don't think I can offer more than that--the industry's only performance-based guarantee, and an outright offer to bring doubter aboard and then write about it.

What do you say?

Dave Culp
KiteShip

[daveculp]

As for being blown the wrong way, the sail does that too. They're both at an angle wrt the boat's heading, so both of them have an athwartship component to their driving force. The keel resists that part, which leaves the forward component to drive the boat through the water. The main difference is that with the kite, you don't need the heavy keel or big wide multihull to resist the heeling moment that you get from a sail.

So ultimately, the kite is no different from a sail. It gets lift from the wind by controlling its angle of attack just like a sail does, so it's being blown in essentially the same direction as the sail. The windspeed is higher at the kite's elevation and it takes up more space. But the main difference is that the kite is tied to a free line, which has several effects:
1) The kite pulls directly along the line holding it, so as long as it's in the air, its force will be partially upward.
2) You can attach the line to the hull at a point where it won't exert any heeling moment, or where it will help counteract the overall moment exerted by the other forces acting on the boat (gravity, bouyancy, lateral resistance, and drag).
3) The direction of the kite's force doesn't change when the boat heels.
4) When the boat heels, the kite may exert a small rotational moment that helps stabilize the boat.
With no heeling moment, the driving force can theoretically be enormously greater, plus the upward component reduces the boat's displacement.

[Edited to make more sense]

Right on, Skippy. Good points. Want a job? ;-)

Dave

[Paul B]

Cool! A doubter.

Really?

W use 1/8" lines for between 35 and 70 meters which we believe are practically the smallest one can handle with gloves on. Smaller kites would need smaller lines which are dangerous to your hands.

Not sure I want to handle a highly loaded 0.125" line, let alone anything smaller. Sure wouldn't want it to wrap any body part, then load up. I'll bet something like that can do a nice job sawing through things like Tuff Luffs, or furled jibs (M24 style).

Most of our currently installed kites are aboard boats that race--Corsair Trimarans, several large multis (Afterburner on the West Coast, Alacrity on the East; both 50'ers, a cat and a tri); many of our kites are aboard one-off multis, in the US, Britain and Australia. Boats from 33-48'. We are constantly pushing for races for our customers to participate in. As with most new technology, organizers are wary of us; we've been banned from some races, embraced by others, and hotly talked about by almost all.

I've yet to see one used in a race, and you're not giving many details here or on your site. What races did Afterburner use their kite in?


Nope. We were scratched late from the Sydney Hobart (which went to windward this year).

Normal, right?

We are currently working on the TransPac (both the transpac and Chi-Mac are Americap races). Newly allowed multihulls in the Pacific Cup may carry kites (we're working on monos for this race, too). Americap requires polars and wind tunnel data--they say--on order to build a VPP for rating OutLeaders. We are not able to fund this work ourselves. Any ORCA race is encouraged to carry kites, but we just got this ruling, so none have, to date. NorCal PHRF is allowing kites on any boat they rate.

Hopefully Americap will die the death it deserves after these races, so no need for the data gathering for that. I would think you would be able to use an off the shelf system for data acquisition to build polars for a specific boat. I'll bet the ACC guys had the ability to do so, and I would expect Langman could do so as well.

PH should rate them, based on real performance, but it will be up to the clubs to allow them. That means PH should probably give provisional ratings until the real potential is determined.

Accurate statement. On our front page, paragraph 2 of our lead article, we admitted we blew the engineering on this kite, could not power it up on first flight. Also where we worked with AAPT's sailmaker. We re-engineered the kite and PAID THEIR SAILMAKER to make the necessary alterations. We still offer our comprehensive money-back performance guarantee--the only one in the business. FWIW, AAPT still owns their kite...

Of course they do. I'm sure it is a good advertising tool. I'd like to see them use it, but better yet let's see a leading OD boat use one in a competitive fleet. The rubber will hit the road there.

Nope. It has been very widely documented that we train new users of our kites without any other sails flying. The crew needs to learn what the kite will, and will not do without interference from other sails, then learn to fly--and launch--behind the main. All of the publicity shots of AAPT were taken during the first--the very first--flight of the giant kite on that boat. FWIW, watch this space; this kite is going to be given a Guinness world record for largest kite ever to pull a boat.

Widely documented? I didn't really get that from the Seahorse article. It seems strange that you would have to unbalance the boat like that.

I have a pair of Doc Martens. I'm going to try and get them a Guinness World Record for the biggerst pair of shoes ever on my feet. Maybe that's not on par with your record, but are you on par with the Hindu who lay on the ground and rolled across India?

I think I covered this above. Have you checked out our discussion list, at http://groups.yahoo.com/group/outleader? Have a look at the customer testimonials there, where folks tell us they've never sailed so fast, never felt so "on rails" sailing offwind, etc??

Jeezis, that guy Alan H is your big testimonial? He's proven, by his own comments on another Board, that he is a terrible sailor. I hope you get someone better than that soon. Seeing that kinda drops confidence in the comments.


Did you read about the older half-tonner in Perth we had 3-sail reaching with our kite--at 11 kts of boat speed (fair for a non-planing 40'er, eh?)?

I hope an "older Half-Tonner" wasn't a 40 footer. Maybe you mean One Tonner?


Have a look at the photos of the J24 pulling a "tugboat" wake in Sydney haarbor last December, doing 9+ kts: http://www.pacificsailingschool.com.au/PhotoAlbums/KiteShip/ ?

I've gone MUCH faster on J24s in the past. Let's see them race it a North Americans around the cans and see how they do.

Did you also read the bit about AAPT being able to pump out all water ballast when flying the kite? This makes the 11-ton boat 3 tons lighter. D'you suppose that may have some effect on her ability to plane out at speed?

I would imagine that they would sail "dry" downwind anyway.


AAPT are our customers, they spent a large amount of money to purchase our kite and to fly our people into Sydney for training; Nicorette are our competitors; how would you have put it, in our place?

Competitors? I would think you should consider Nicorette to be POTENTIAL CUSTOMERS.


I'm pulling your leg a little bit here, Paul. Your profile says you're in California. Why don't you get in touch with me, and I'll arrange for you to take a test sail? You can then come back here and tell of your own first-hand impressions, good or bad. I don't think I can offer more than that--

I'm taking the piss a bit as well. I'm in LoCal, not NorCal. If this actually catches on as a viable alternative I'm sure I'll have opportunities to Do It.

[daveculp]

Dude, I'm not gonna rise to any of the above. I've made you an offer. I've got boats up and down the coast, have steered you to a number of people who have done it, not pissed on it from the danger of their armchair.

We're inclusive in our approach; we'd love to include you. Frankly, I was always sure you'd stay away. Have fun anyways.

Dave

[Paul B]

Dude, I'm not gonna rise to any of the above. I've made you an offer. I've got boats up and down the coast, have steered you to a number of people who have done it, not pissed on it from the danger of their armchair.

We're inclusive in our approach; we'd love to include you. Frankly, I was always sure you'd stay away. Have fun anyways.

Dave

I see you modified your reply. Seeing as how I'm currently challenging the local establishment in my own way, I'm not quite a fit for what you originally wrote.

You've been making some pretty aggressive statements here. Your ideas might be earth shaking, maybe not. You haven't provided any real data yet, and you don't seem to like to answer questions head on. As Dr. Deming used to say, "There are no opinions, there is only data."

Let's see your tech in the crucible before we make any judgement.

[usa2]

im not going to straight out say that i dont believe in kites, because that would be unfair to those who sail with them and know more about them than i do. I think that off the wind, they are usefull, and the OUTLEADER kites are a good idea that shouldnt be banned by rating rules. However, I still question the idea of a boat being able to sail upwind faster with a kite than without. Does anyone know what would happen if you gave an IACC boat an upwind kite. This would all be theoretical, of course. Right now, those boats can achieve at least 13 knots hard on the wind, and some are rumored to have slightly faster than that. So say that you give an 85 footer a large upwind kite, will it be able to go at least 13 knots? Off the wind, an Outleader type kite should murder a conventional spinnaker, and that is what they are designed to do, as they are spinnaker replacement kites. Does anyone have an ideas on this?
thanks-
-usa2

[John Perry]

However, I still question the idea of a boat being able to sail upwind faster with a kite than without. -usa2

My view would be that future kite designs may well achieve better windward performance than is possible with conventional sails but current kite designs will not achieve this. The lift to drag ratio of the rig (using the aerodynamisist's meaning for the term lift) is crucial to optimum windward performance and from a discussion with pioneer kite sailor Cory Rosseler a couple of years back I understand that the lift to drag ratio of typical kite sailing kites is in the region of 3:1, including line drag. This is a poor lift to drag ratio compared with that which can be achieved with wing masted rigs and solid wing sails. However I believe that the potential exists for much higher lift to drag ratio 'kites', which could for example have ridgid aerofoils and automatic (electronic) controls to allow flight control without multiple tethering lines. Such 'kites' may or may not prove to be practical for general purpose sailing but I think the potential must exist for speed sailing and record setting over both short and long distances.

If one were to optimise a kite powered craft for upwind performance I dont think an america's cup yacht would be a good starting point. One of the big advantages of kite rigs is that they do not necessarily impart any heeling moment on the craft they are attached to, and can indeed be arranged to stabilise a craft in heel. Hence a ballast keel is not needed on a kite craft, and would be just unecessary weight.

[Paul B]

I have assumed that kite boards must be able to go upwind somewhat, at least a close reach. Am I wrong about this? Otherwise how do they get off the beach during an on-shore, and back to the beach with an off-shore?

So wouldn't those same type of kites be able to sail "upwind" on bigger boats? Anyone know how close winded you can get on a kite board (tacking angle)?

VMG is more to the point than discussing ultimate speed. ACC boats might go 13 knots upwind as stated by USA2, but it's the VMG that is more important. They tack in less than 70 degrees, so they are really putting that speed in the right direction.

[Skippy]

How is the drag distributed thoughout the rig? I would expect the structural members to be lighter & thinner without any heeling moment, so that leaves the line?

[daveculp]

My view would be that future kite designs may well achieve better windward performance than is possible with conventional sails but current kite designs will not achieve this. The lift to drag ratio of the rig (using the aerodynamisist's meaning for the term lift) is crucial to optimum windward performance and from a discussion with pioneer kite sailor Cory Rosseler a couple of years back I understand that the lift to drag ratio of typical kite sailing kites is in the region of 3:1, including line drag. This is a poor lift to drag ratio compared with that which can be achieved with wing masted rigs and solid wing sails. However I believe that the potential exists for much higher lift to drag ratio 'kites', which could for example have ridgid aerofoils and automatic (electronic) controls to allow flight control without multiple tethering lines. Such 'kites' may or may not prove to be practical for general purpose sailing but I think the potential must exist for speed sailing and record setting over both short and long distances.

If one were to optimise a kite powered craft for upwind performance I dont think an america's cup yacht would be a good starting point. One of the big advantages of kite rigs is that they do not necessarily impart any heeling moment on the craft they are attached to, and can indeed be arranged to stabilise a craft in heel. Hence a ballast keel is not needed on a kite craft, and would be just unecessary weight.

Hi John,

It's been awhile. How are you doing? You make some excellent points.

Kites have improved a good deal; on short lines, the best regularly manage 5:1 to 6:1, including lines. This is on a par with a good soft sail rig, including the mast plus standing/running rigging, but not as good as a wingsail, of course.

There are far more weatherly kites than those currently used for kitesurfing, which are specialized for power, not efficiency. However, putting high efficiency kites on boats has a fundamental physics problem--an efficient kite can dive, across the wind window, at 3-4 times wind speed. In doing so, the energy they extract from the wind increases by a factor of 9-16 times(!) It is this wide max/min ratio which is hard to deal with. Fine for kitesurfers; not so fun for the family cruiser. Still, there are solutions, some of which are nearing the market.

Dave

[usa2]

so, like as Paul B said, IACCs tack through about 70 degrees. I think the apparent wind angle they sail to upwind is some ridiculously small number like 30 degrees...maybe a even a little less than that. And they do 13 knots. Could a well designed and built upwind kite be able to produce that kind of efficiency going to weather? I think the kites are obviously the answer for outright speed records, but typical racing sailors, whats the use of a kite if its illegal. Also, if say an upwind kite really did work, how does one tack the boat?

[daveculp]

How is the drag distributed thoughout the rig? I would expect the structural members to be lighter & thinner without any heeling moment, so that leaves the line?

It's some of both, Skip. An inflated kite on the end of a string--which CANNOT weigh more than perhaps 5-10 pounds--cannot typically maintain as efficient a shape as a rigid wingsail weighing 20-40 times as much.

Plus the lines are pure drag--no lift. (Interestingly, I am just now in the California desert doing some research for the Army into kite line drag and how to reduce it practically. OK, they call 'em "parachutes" but we see kites. ;-)

It's physically (well, theoretically) possible to make kites better than the best boat wings, but it's not likely to come to pass, for cost and safety considerations (think hard-wing kites falling on your head), though guys have achieved 12-15:1 with experimental kites. These kites look suspiciously like large model sailplanes, tethered to the ground and flown as kites.

In the meantime, kites can out-pull any sail of the same size (increased wind at altitude; ability to "work" the kite, keeping it always moving faster than the boat), can lighten the boat by 50-70% by eliminating ballast, beam, strength in the ends of the boat (kites only attach amidships), and reserve buoyancy, which kite boats do not need. They also can pull non-sailboats, such as power vessels, ships, oil rigs and icebergs. Since they are self-supporting and self-deploying, they make dandy "get home" devices, for self-rescue and even for finishing races without the rig. We've got an article on our website about our trip from the Caribbean to the Upper Chesapeake last May with a dismasted racing tri.

BTW, I'm talking about kites in general, not about OutLeader kites, for the trolls listening in. ;-)

Dave

[daveculp]

so, like as Paul B said, IACCs tack through about 70 degrees. I think the apparent wind angle they sail to upwind is some ridiculously small number like 30 degrees...maybe a even a little less than that. And they do 13 knots. Could a well designed and built upwind kite be able to produce that kind of efficiency going to weather? I think the kites are obviously the answer for outright speed records, but typical racing sailors, whats the use of a kite if its illegal. Also, if say an upwind kite really did work, how does one tack the boat?

USA2; NOTHING can beat an IACC boat to windward, short of the best C-cats. They don't tack through 70, but more like 50 degrees. They sail within 15-18 degrees of apparent wind. (You may know that we developed the OutLeader kite for BMW Oracle Racing, for the 2003 America's Cup. Not an upwind kite, but we spent a good bit of time aboard these boats. They are AMAZING boats.) In anything under about 10-11 kts, an IACC boat can make good either dead to windward OR dead to leeward (VMG), better than the true wind speed. Nothing short of C-cats (and maybe A's), land sailers and iceboats can equal this.

Kites aren't going to beat $100 million world-class raceboats. They CAN beat whatever you sail, though. ;-)

Kites are not illegal in sailboat racing, with a very few exceptions. The issue (the reason for this thread) is the ISAF's not recognizing outright speed records under kites--they have ALWAYS recognized kite boat speeds.

Kites do not tack, they wear. It will be many years before a pure kite boat can beat even good boats around the cans--which is why my company is focusing on downwind courses anly at present, where kites have their greatest advantage. (Yeah, including downwind courses around the cans)

Dave

[Paul B]

USA2; NOTHING can beat an IACC boat to windward, short of the best C-cats. They don't tack through 70, but more like 50 degrees. Dave

Not Quite.

Watching the last couple of LVCs and ACs you could track all the boats tacking through about about 65 degrees. At a TWA of 32, TWS 15, Speed 12, you have an AWA of about 18.

If you try a TWA of 25 (tacking through 50) at the same wind and boatspeed you get an AWA <14. Maybe they can punch up to that for short periods, but they don't sustain that.

[daveculp]

Not Quite.

Watching the last couple of LVCs and ACs you could track all the boats tacking through about about 65 degrees. At a TWA of 32, TWS 15, Speed 12, you have an AWA of about 18.

If you try a TWA of 25 (tacking through 50) at the same wind and boatspeed you get an AWA <14. Maybe they can punch up to that for short periods, but they don't sustain that.

There, see, you CAN post without trolling. ;) I'll concede your numbers, they sound good; though have been aboard AC's short-tacking through +/- 50 degrees. Pro'lly short-time stuff, as you suggest.

Dave

[usa2]

AC boats cant sail 13 knots while tacking through 50 degrees. They can sail that high, but in that case, the wind is lighter and the apparent wind is the same...Which i believe is about 25 degrees off the wind. In all the Cup races i have seen, the boats dont tend to point any higher than 25 degrees, or so i have noticed. As the wind picks up, they will start tacking wider angles, but the apparent wind remains the same. So in anything under 10 knots the boats will be tacking through about 50 degrees, but I was referring to when the boats are traveling at full speed upwind, which is 13 knots in about 20+ knots of wind. The only time they will start pointing that high while the wind is strong enough to have them going 13 knots is if they are low on a layline and need to get above the mark. If the wind is moderate, then on average they will tack through about 65 degrees.

[FAST FRED]

Many decades ago someone asked the AYRS (Amateur Yacht Research Society) in England what would be the most "efficent" sail boat.

The response was a submerged boat towed by a kite,

Looks like were half way there!

FAST FRED

[Paul B]

AC boats cant sail 13 knots while tacking through 50 degrees. They can sail that high, but in that case, the wind is lighter and the apparent wind is the same...Which i believe is about 25 degrees off the wind. In all the Cup races i have seen, the boats dont tend to point any higher than 25 degrees, or so i have noticed. As the wind picks up, they will start tacking wider angles, but the apparent wind remains the same. So in anything under 10 knots the boats will be tacking through about 50 degrees, but I was referring to when the boats are traveling at full speed upwind, which is 13 knots in about 20+ knots of wind. The only time they will start pointing that high while the wind is strong enough to have them going 13 knots is if they are low on a layline and need to get above the mark. If the wind is moderate, then on average they will tack through about 65 degrees.

I think you must be mixing apples and oranges at times, regarding TWA and AWA. The boats do not sail within 25 degrees TWA in light air, then drop off 7 or more degrees to 32+ when "the wind picks up." They may sail as low as 25 degrees AWA in really light stuff, but that sounds too low unless they are accelerating out of a tack. Can you cite your reference for the numbers you're claiming?

In fact, in light air as the boatspeed approaches the TWS the AWA moves Forward. In light air monohull boats in displacement mode normally sail lower angles than they do as the wind fills. Not only are you working against the TWA/AWA shift, but in light air your sails are fuller.

Of course, if the chop increases with the TWS increase the boats may need to foot a bit to get to targets.

Also, if you are talking about a planing boat (NOT an ACC) it can be beneficial to foot to transition to planing.

[daveculp]

Many decades ago someone asked the AYRS (Amateur Yacht Research Society) in England what would be the most "efficent" sail boat.

The response was a submerged boat towed by a kite,

Looks like were half way there!

FAST FRED

I'm guessing you saw this in Scientific American magazine. Theo Schmidt has done a good bit of work on efficient boats; and first (to my knowledge) suggested submerging the hull (to abvoid surface waves) connected to a kite (to avoid all the drag issues associated with heeling). Of course, he didn't adress the issue of the flying lines--both above and below the water.

Dave

[daveculp]

I think you must be mixing apples and oranges at times, regarding TWA and AWA. The boats do not sail within 25 degrees TWA in light air, then drop off 7 or more degrees to 32+ when "the wind picks up." They may sail as low as 25 degrees AWA in really light stuff, but that sounds too low unless they are accelerating out of a tack. Can you cite your reference for the numbers you're claiming?

In fact, in light air as the boatspeed approaches the TWS the AWA moves Forward. In light air monohull boats in displacement mode normally sail lower angles than they do as the wind fills. Not only are you working against the TWA/AWA shift, but in light air your sails are fuller.

Of course, if the chop increases with the TWS increase the boats may need to foot a bit to get to targets.

Also, if you are talking about a planing boat (NOT an ACC) it can be beneficial to foot to transition to planing.

You turned it over yourself, Paul. As apparent draws forward, the boat must sail lower, not higher, thus USA2's "wind picks up" comment. I suspect you're real doubt is whether ACC boats can sail as high as 25 degrees (true) in light wind. I can assure you that they can. As soon as they can get attached flow across the keel (3-4 kts if the lift demands aren't too high), they are astonishing light wind fliers, and are extensively optimized for upwind (and also downwind) VMG work under those conditions.

I think USA2 cited actual readouts from the extensively available Virtual Spectator files of every race in the 2002-3 LVC and the 2003 AC. I would point you to these same sources, and include personal experience of my own, aboard one of the fastest ACC's (USA 76) and "looking over the shoulder" of the crew at the actual onboard instruments as they trained.

Dave

[Paul B]

You turned it over yourself, Paul. As apparent draws forward, the boat must sail lower, not higher, thus USA2's "wind picks up" comment. I suspect you're real doubt is whether ACC boats can sail as high as 25 degrees (true) in light wind. I can assure you that they can. As soon as they can get attached flow across the keel (3-4 kts if the lift demands aren't too high), they are astonishing light wind fliers, and are extensively optimized for upwind (and also downwind) VMG work under those conditions.

I think USA2 cited actual readouts from the extensively available Virtual Spectator files of every race in the 2002-3 LVC and the 2003 AC. I would point you to these same sources, and include personal experience of my own, aboard one of the fastest ACC's (USA 76) and "looking over the shoulder" of the crew at the actual onboard instruments as they trained.

Dave

Wow, that's some strange reply. I think you better read my message again, draw some diagrams, and do the math.

The original claim was that you know ACC boats tack through 50 degrees. They don't. If you know this is shown on a particular VS file please provide a link.

As for "personal experience", it is rarely data with confidence. Your claim is right up there with the guy "who was there" when an Open 60 planed upwind into a 4 foot chop. No one else has ever seen an Open 60 plane upwind, not even the current boats with more sail carrying power than the boat he was on. Anecdotal evidence often morphs as time passes.

But I'm sure I won't convince either of you that you are mistaken, so I won't bother.

[usa2]

boats "drop off" the wind when it "picks up" because the AWA moves FORWARD. i dont think anything i said implied anything other than that.

[Paul B]

boats "drop off" the wind when it "picks up" because the AWA moves FORWARD.

No, it doesn't.

As BS approaches TWS the AWA moves forward.

Hypothetically (never happen in reality) your ACC boat is cruising along at hull speed of 13 knots BS, 32 degrees TWA, in 13 knots TWS. The AWA would be 16 degrees.

The wind "picks up" to 15 knots. You don't go any faster (ACC boats don't plane upwind) AND you decide to continue to sail at 32 degrees TWA. Your AWA is now 17.2 degrees. The BS vector is now proportionally less than the TWS vector. You could have poked up to 30 degrees TWA to retain the same 16 degrees AWA you had at the lower wind speed.

The wind "picked up" but the AWA did not move forward. It moved aft.

I've sailed a lot of high perfomance keelboats over the years. I've never encountered one that sailed higher in lighter air and went bown down as the breeze came on (until overpowered). Again, you might have to go bow down as the sea state changes, but that is not relevant to the discussion.

You stated that ACC boats could sail at 25 degrees TWA, but only in light air. Again, please cite some data we can review.

[usa2]

The virtual spectator readouts during the LV Cup and the AC itself and watching on TV. Also saw UBS trophy Newport.
I think maybe here we are misinterpreting each others comments to a certain degree, and also maybe we understand certain concepts differently, because on every boat that i have sailed on or seen sailing, or even read about sailing, if the wind speed and/or boatspeed increases, the AWA moves forward.
Lets say that USA-76 is doing 13 knots upwind in 18 knots of wind. The wind increases to 25 knots. If ORACLE was sailing at 30 degrees TWA in 18 knots of wind and the wind speed increases to 25 knots and they are still sailing 30 degrees TWA, the apparent wind speed increases while moving forward. Therefore, ORACLE falls off a little to keep the AWA at their boats optimum. I have never heard of a boat that the AWA angle moves aft if the boat keeps its course and speed as the wind increases. The AWA moving forward is the reason why all the supermaxis dont have symmetrical spinnakers. They are so fast that even if they sail relatively deep, the AWA angle is on the beam or forward of it. An example of this is Nicorette finishing the Sydney-Hobart race in 6 knots of wind. They were doing thirteen knots with an A-sail and main. So if someone can explain how its possible for the apparent wind angle to move aft with out slowing the boat, decreasing the wind speed, or turning the boat away from the wind, it would be appreciated.

[daveculp]

No, it doesn't.

As BS approaches TWS the AWA moves forward.

Hypothetically (never happen in reality) your ACC boat is cruising along at hull speed of 13 knots BS, 32 degrees TWA, in 13 knots TWS. The AWA would be 16 degrees.

The wind "picks up" to 15 knots. You don't go any faster (ACC boats don't plane upwind) AND you decide to continue to sail at 32 degrees TWA. Your AWA is now 17.2 degrees. The BS vector is now proportionally less than the TWS vector. You could have poked up to 30 degrees TWA to retain the same 16 degrees AWA you had at the lower wind speed.

The wind "picked up" but the AWA did not move forward. It moved aft.

I've sailed a lot of high perfomance keelboats over the years. I've never encountered one that sailed higher in lighter air and went bown down as the breeze came on (until overpowered). Again, you might have to go bow down as the sea state changes, but that is not relevant to the discussion.

You stated that ACC boats could sail at 25 degrees TWA, but only in light air. Again, please cite some data we can review.

You're looking at only one end of the equation, Paul--when wind gets high enough that the boat cannot accelerate. Others look at the regime where the boat CAN accelerate, and does.

You said, "I've sailed a lot of high perfomance keelboats over the years. I've never encountered one that sailed higher in lighter air and went bown down as the breeze came on (until overpowered)." and you also said, "As for "personal experience", it is rarely data with confidence. Your claim is right up there with the guy "who was there"..."

Which is it my friend; you can't actually have it both ways. Are you suggesting that your own experience/memory is inaccurate? Or that only OTHERS' experience is open to question? How many hours do you have in IACC boats? I'm no expert; I've maybe 100 hours in them. You must have much more, to make the statements you are making about a class which two of us, independently, are declaring is significantly different from "a lot of high performance keelboats." Or perhaps you're an IACC designer? Statistician? Tactician? Navigator?

I guess there's no arguing with an "expert." Have a nice day.

Dave

[usa2]

In either case that Paul B mentions, the AWA will still move forward...

[Paul B]

The virtual spectator readouts during the LV Cup and the AC itself and watching on TV. Also saw UBS trophy Newport.

Then you were seeing something different than some others who logged the same thing.

I think maybe here we are misinterpreting each others comments to a certain degree, and also maybe we understand certain concepts differently, because on every boat that i have sailed on or seen sailing, or even read about sailing, if the wind speed and/or boatspeed increases, the AWA moves forward..

The "and/or" is where your mistake is. Increases or decreases in TWS and BS are independent variables in the equation. It is the relation between these two variables that determines the increase/decrease of the AWA (given a constant TWA). If BS doubles while TWS only rises by 10%, then the AWA is going to go Forward. If BS Doubles while TWS quadruples then the AWA is going to move back. The amount of movement is dependent on the TWA.


Lets say that USA-76 is doing 13 knots upwind in 18 knots of wind. The wind increases to 25 knots. If ORACLE was sailing at 30 degrees TWA in 18 knots of wind and the wind speed increases to 25 knots and they are still sailing 30 degrees TWA, the apparent wind speed increases while moving forward. Therefore, ORACLE falls off a little to keep the AWA at their boats optimum..

13 knots in 18 knots at 30 degrees TWA is 17.5 degrees AWA.

13 knots in 25 knots at 30 degrees TWA is 19.8 degrees AWA. That is not moving forward.

However, if the BS went up in a greater proportion to the TWS then the AWA would move forward. In your example, if the TWS goes from 18 to 25 that is a factor of 1.39. So if BS went up 1.4x (or more) 13 knots (18.2 knots) the AWA would move forward. So 18.2 at 30 degrees in 25 knots= 17.4 degrees AWA.



I have never heard of a boat that the AWA angle moves aft if the boat keeps its course and speed as the wind increases. The AWA moving forward is the reason why all the supermaxis dont have symmetrical spinnakers. They are so fast that even if they sail relatively deep, the AWA angle is on the beam or forward of it. An example of this is Nicorette finishing the Sydney-Hobart race in 6 knots of wind. They were doing thirteen knots with an A-sail and main..

The reason for this is their relative BS compared to the TWS. If you are moving at or above the TWS when sailing downwind the wind comes forward. Actually, if the TWS DECREASES and you maintain the same BS and angle the AWA will move forward. IF your BS decreases and you maintain speed and heading the wind will move aft. It is really simple vectors, shouldn't be that hard to follow.

This is the the whole idea behind "Sailing Esses" downwind. You heat to increase BS relative to TWS, this brings the wind forward, which allows you to bear off and milk the AWA and AWS until your BS begins to drop (repeat). Big boats like Nicorette do well with the speed builds and really build AWS.

So if someone can explain how its possible for the apparent wind angle to move aft with out slowing the boat, decreasing the wind speed, or turning the boat away from the wind, it would be appreciated.

As I said above, simple vector analysis. The BS should be seen as a vector of "WS" right on the nose. If this vector increases in relation to the TWS from some TWA, then the AWA moves toward the BS vector. If you decrease the BS vector relative to the TWS vector the AWA moves toward the TWS vector.

[usa2]

i think maybe we are misunderstanding each other terms here of "forward" and "aft" .

[usa2]

If like you are saying, that the AWA moves AFT when the wind increases while traveling upwind, that would suggest that if the wind moved aft far enough the IACC could set a Code Zero in over 20 knots of wind, while on the wind. There are reasons why Code Zeros are built for light air. Im not trying to get into an argument here, but may have already, but conventional logic and facts suggest that the AWA moves forward

[Paul B]

You're looking at only one end of the equation, Paul--when wind gets high enough that the boat cannot accelerate. Others look at the regime where the boat CAN accelerate, and does.

Well Dave, let's look at one of your earlier claims:

In anything under about 10-11 kts, an IACC boat can make good either dead to windward OR dead to leeward (VMG), better than the true wind speed.

I'm not sure I agree with your premise, but let's say you are right about this one thing.

So to have a faster VMG upwind than the TWS you have to be going really fast. I'll be conservative and say 10% greater than TWS. It will be more in practice, but I'll give you a break.

So let's say 10 knots BS in 9 knots wind. Let's give USA2 his 25 Degrees. AWA would be 11.8 degrees. I'm sure an Aeronautical Engineer like yourself would agree this isn't going to work, but let's move forward.

If the boat decelerates to 9 knots the AWA goes back to 12.5 degrees. You hit a wave, boat slows, AWA comes back, jib goes out, boat accelerates, AWA comes forward, jib comes in...all in the same TWS and heading. Obviously in the real world you would push the bow down as well to accelerate, requiring additional jib out.

As long as BS acceleration proportionally outstrips TWS the AWA will move forward. When it is reversed the AWA moves back. It is the relationship of these two variables that produce the result.


You said, "I've sailed a lot of high perfomance keelboats over the years. I've never encountered one that sailed higher in lighter air and went bown down as the breeze came on (until overpowered)." and you also said, "As for "personal experience", it is rarely data with confidence. Your claim is right up there with the guy "who was there"..."

Ah, but my "personal experience" also includes some calculations to back them up. I'm not simply stating things like "AWA moves FWD as TWS increases" without proof. When will you provide calculations or data to support your end?

Which is it my friend; you can't actually have it both ways. Are you suggesting that your own experience/memory is inaccurate? Or that only OTHERS' experience is open to question? How many hours do you have in IACC boats? I'm no expert; I've maybe 100 hours in them. You must have much more, to make the statements you are making about a class which two of us, independently, are declaring is significantly different from "a lot of high performance keelboats." Or perhaps you're an IACC designer? Statistician? Tactician? Navigator?Dave

Dave, I'm nobody. I could tell you I've been a significant part of crews, as primary trimmer or tactician, that have won multiple National Championships and virtually every major keelboat series in California at one time or another. I could tell you I worked in the design office of a well known ACC designer, before the ACC rule existed. I could tell you I recently had dinner with a very famous Design Director for a winning ACC syndicate. But none of that matters, does it?

When will you provide any calculations or data to support your claims? I mean, while I am nobody you are someone trying to convince the world you know what the hell you are talking about. Arguing against simple mathematics isn't making you look too good.

[Paul B]

If like you are saying, that the AWA moves AFT when the wind increases while traveling upwind, that would suggest that if the wind moved aft far enough the IACC could set a Code Zero in over 20 knots of wind, while on the wind. There are reasons why Code Zeros are built for light air. Im not trying to get into an argument here, but may have already, but conventional logic and facts suggest that the AWA moves forward

Well, the AWA can never move farther aft than the TWA, can it? Vectors, two components, BS and TWS. The resultant AWA must fall between heading (vector of BS) and TWA (vector of TWS). So if you keep the TWA at 32, or 25, or whatever, the AWA can't get out to 40 or 50, or useful Code Zero angles. The AWA will be somewhere between Zero and the TWA.

Code Zeros are not allowed on "Upwind" legs during the AC or LVC. The ones used in the Volvo Race were really genoas, very large masthead ones. So it would make sense to use them in light air, if you could get the sheeting angles in enough. Most boats do use their biggest genoas in light air.


I don't want to argue with you either, but your conclusions are not the result of Logic or Facts. They are your opinion, and are incorrect.

[usa2]

Paul B,
could you explain the formulas you are using to come up with these AWA please?
thanks-
-usa2

[Paul B]

Paul B,
could you explain the formulas you are using to come up with these AWA please?
thanks-
-usa2

I'm no math teacher, as you can see from my writings. However, I think you might use the diagrams from this site to make your own spreadsheet:

http://www.sailingusa.info/true_wind_calculator.htm

Just one last example that might make things easier:

Boat is at rest with the wind coming from abeam, 90 degrees. TWA is 90, AWA is also 90, regardless of TWS.

Boat is in zero wind and is motoring forward. The TWA is 0 degrees, winddex is pointing straight forward, regardless of speed.

Boat is at rest, anchored, wind on the beam again, at 5 knots. AWA is also abeam, right? Sails are raised, anchor is lifted and boat starts moving forward. TWS is still 5 knots. Boat reaches 5 knots of BS (hullspeed). Where is the AWA? It has pulled forward to 45 degrees, right? Half of the AW from Zero and Half from 90 degrees.

Now increase the TWS to 10 knots. BS remains 5 knots. Now twice the component comes from abeam compared to from the nose. Increase in wind velocity relative to the BS. With twice the velocity from the wind the AWA will shift aft toward the beam, to approximately 2/3 of the angle from Zero to 90 degrees.

If the boat then dropped the anchor and slowed to no BS then the TWS would again be increasing in relation to the BS, and eventually the AWA would be at 90 degrees.

So, on the same reach angle in the same wind, Nicorette going twice the windspeed will have the AWA full forward, Code Zero strapped, while the ferro cement slug dead on her stern will be seeing a near beam reach as she plods along at a quarter of the windspeed. It is all based on the proportions of the forces on each vector.

[CT 249]

"On the same reach angle in the same wind, Nicorette going twice the windspeed will have the AWA full forward, Code Zero strapped"

And if it's the previous (1999) Nicorette with the original rudder in, the driver will be alternating between going "aaahhhh this is such fun, what a well balanced helm" and then "oooooooooooooohhhh shit" as the rudder loads and unloads as she speeds up and down swells. Never felt anything like that foil for shifting CLR back and forth but I only drove her once.

[Paul B]

"On the same reach angle in the same wind, Nicorette going twice the windspeed will have the AWA full forward, Code Zero strapped"

And if it's the previous (1999) Nicorette with the original rudder in, the driver will be alternating between going "aaahhhh this is such fun, what a well balanced helm" and then "oooooooooooooohhhh shit" as the rudder loads and unloads as she speeds up and down swells. Never felt anything like that foil for shifting CLR back and forth but I only drove her once.

Well, now we are quite a bit off the original topic of ISAF and Kites.

I need to ask, what was the problem with that rudder and setup? Too much counterbalance? Not enough? Was there something about that foil shape that was causing stall at normal operating angles?

Are you sure it was CLR shifting and not CE?

I'm sure the crew was full pro, so I doubt it was the normal problem of overstrapping the kite on the way down the wave (as the AWA shifts forward), then not enough ease as you decelerate at the bottom (as the AWA shifts back).

By the way, have you ever seen a boat tack through 50 degrees? I know the 18s tack through a pretty narrow angle, I'm guessing in the 65-70 degree range?

[Skippy]

Speaking of 50-degree tacks, is that really where you get max VMG even in an IACC boat? If you fall off just a little, it does wonders for the AWA even at higher speed given equal VMG.

[daveculp]

Speaking of 50-degree tacks, is that really where you get max VMG even in an IACC boat? If you fall off just a little, it does wonders for the AWA even at higher speed given equal VMG.

Absolutely not, Skippy. IACC boats can tack through 50-60 degrees and they can also make good better than the wind speed dead to windward, but NOT at the same time. It's interesting that the "mathematical" arguments here work so quickly to put words into one's mouth, but the facts are (obviously) somewhat different.

FWIW, it is possible to predict the best course for VMG, up or downwind for a given set of circumstances. I don't have my Marchaj with me at the moment, but it's a simple formula; if you have accurate drag angle data on both the hull/keel and the rig. ("drag angle" is the arc tan of the L/D of either the rig or the hull/keel--it is easier to measure than L/D, especially with models or towing full size hulls). Drag angles of both are needed to predict optimal course. The "hook" is that these angles change significantly for most monohull sailboats as their speed increases, due to hull speed limitations on non-planing, non-multihulls. OTOH, understanding the formula--and how it's derived--will help you to better your VMG work in any boat--it can improve your "intuition" at the helm. See Aero-hydrodynamics of Sailing, by Marchaj.

Dave

[usa2]

we should make an IACC thread, cuz if you read the title of this one its something to do with kites....

[SailDesign]

I'm sure the crew was full pro, so I doubt it was the normal problem of overstrapping the kite on the way down the wave
Nicorette uses a KITE? Well, that means we are right on topic, then :)

Steve "who WAS there..."

[usa2]

ya, but Nicorette's "kite" hasnt been banned by the ISAF...yet

[CT 249]

Well, now we are quite a bit off the original topic of ISAF and Kites.

I need to ask, what was the problem with that rudder and setup? Too much counterbalance? Not enough? Was there something about that foil shape that was causing stall at normal operating angles?

Are you sure it was CLR shifting and not CE?

I'm sure the crew was full pro, so I doubt it was the normal problem of overstrapping the kite on the way down the wave (as the AWA shifts forward), then not enough ease as you decelerate at the bottom (as the AWA shifts back).

By the way, have you ever seen a boat tack through 50 degrees? I know the 18s tack through a pretty narrow angle, I'm guessing in the 65-70 degree range?

Ummm, it was about 4 years ago and I only sailed her a coupla times. I think it was a function of the foil shape for some reason reacting wildly to different speeds, in terms of the Centre of Lift (IIRC) of that particular appendage making the rudder go more or less balanced as the boat accelerated down swells or slowed up the back of them. It was wrong of me to say it was the CLR.

Why it did that, I don't know; isn't that a problem with laminar flow sections or something? AFAIK it is a recognised effect that becomes worse with foils of certain sections; I know of cruising cats with long keels that wander terribly because the C of L or whatever it is wanders up and down a certain % of the foil as speed changes, and when the boat is quite fast down waves and has a long keel the CLR can be moving several feet in a few seconds.

The Nicorette guys had built a new rudder but put the old one back in for farting around. I think I asked them about the reason for the change and that's where my vague memory of the cause comes from. You could definitely feel it on the helm.

It wasn't stalling, it wasn't crew problems. A mate had the same problem with a Jutson rudder on his 10m tri.

I haven't seen a boat go through 50, but I haven't been on an IACC boat and the only one sailing around here is a dog. Dunno about the 18s tacking angles, sorry. It's fairly "normal" from memory.

PS to all; sorry "kite" was just used as Aussie sailing slang term for spinnaker.

I may have a kite sail on a proa in two days time, should be fun.